Improved process for amalgamating ores



UNITED STATES PATENT OFFICE.

V. F. STEWART, OF AUSTIN, NEVADA TERRITORY.

IMPROVED PROCESS FOR AMALGAMATING ORES.

Specification formiin art of Letters Patent No. 45,534, dated December20 1864.

n I a To on whom it may concern:

Be it known that I, V. F. STEWART, of the city of Austin, in the countyof Lander and Territory of Nevada, have invented a new and Improved Modeof WTorking Silver Ores and for Saving the Amalgam and Quicksilver inQuartz-Mills; and I do hereby declare that the following is a full andexact description of the said invention.

In working silver ores the waste and loss of amalgam and quicksilver isoccasioned by an excess of sulphur and mineral oxides which exist in thepowdered ore or pulp. The mercury is carried off in the washing in thecondition of a protosulphuret of mercury, and the amalgam is carried offby becoming attached to the oxidized particles of lead, iron, antimony,bismuth, &e. To prevent this waste and loss, and to work the ores moreeconomically and expeditiously, is the purpose and claim of mydiscovery.

Process for working silver creel-First, crush the ore in the usual waywith stampers in a battery; second, place the powder or pulp in tubs orpans and saturate with hot water or steam; third, to the pulp add tenper cent. of common salt, or sufficient quantity to reduce the silver toa chloride, then stir for half an hour; fourth, add sufficient metalliciron (filings, if possible) to reduce the chloride to muriate of iron;fifth, add sufiicient quicksilver to amalgamate all the silver in thepulp; (as ores differ greatly in richness, experience will have todetermine the quantity to be used;) stir half an hour sixth, to onehundred pounds of gray sulphuret ore use two or three ounces ofcarbonate of potash; (the quantity must be increased or decreasedaccording to the oxidized particles which appear in the pulp;) also, addone pennyweight of pulverized metallic copper and ten grains ofprotoxide tin; stir for two hours in warm water; seventh, dilute oneounce commercial nitric acid in two gallons water; pour into the pulpand stir for ten minutes; then add two gallons strong lime-water(carbonate of lime) and stir for fifteen minutes; eighth, wash the pulpin clear water; draw off the quicksilver and separate the amalgam bystraining through buckskin or canvas.

It will be seen that the above proportions are given as an approximateidea of what is requisite for one hundred pounds of pulp; but as thereare scarcely two mines in this country the ores of which are identical,much will depend upon the experience and judgment of the amalgamator inrelation to the quantities to be used. I

In addition to my mode of working the ores from the battery, I save theamalgam and quicksilver which may have escaped in the tailings ofquartz-mills, as follows: The tailings or sand is placed in a vat or tubcontaining a bath of water, carbonate of potash, protoxide of tin,andcopper filings. The mass must be stirred occasionally, and should remain in the bath four or five hours. (The pro portions of eachingredient must be determined by the condition ofthe pulp.) The tailingsare then taken from the bath and passed through an oscillating wiresieve (ordinary meal-sieve.) This will divide the quicksilver intoniyriads of fine particles and cause it to gather into a mass instantly,for the reason that the sieve literally skins each globule from itstenacious coating of protosulphuret. After sifting, the pulp issubmitted for a few minutes to a bath of weak dilute nitric acid. Thiswill form nitrate of lead of any litharge which may re main in the mass;and nitrate of lead is soluble in water. The acid will partially cleansethe mercury and prepare it for manipulation. The pulp must then bewashed in cleanwater and the precipitated quicksilver drawn off. Theremaining mass will be a dingy-black amalgam, having the appearance'andconsistency of black lead and grease. It is'then rubbed and washed in acommon porcelain mortar, first with a hard pestle and then with a gumelastic pestle, until all the sulphur is driven off and the wholereduced to clean quicksilver.

The philosophy of the above process may be briefly stated as follows:Most of our silver ores are either sulphurets of silver and iron, silverand antimony, silver and lead, silver and arsenic, or some othercompound of sulphur. )Vhen the pulverized sulphurets come in contactwith mereury,vast quantities of the latter are converted into aprotosulphuret of mercury and carried. off in washing. It is well knownthat native or metallic copper has a strong affinity for quicksilver,and hence its use in precipitating the mercury and liberating thesulphur when applied to the protosulphuret. The remarkable affinitybetween A new and improved mode of working silver ores and savingamalgam and quicksilver, as above described.

In testimony whereof I have hereunto set my hand and seal, in the cityof Virginia, Territory of Nevada, this 10th day of June, A. D.

W. F. STEWART. [L. s] In presence of- H. H. WINOHELL, I. W. SHIELDS.

